This is a Plano-Concave Lens from Standa, a renowned vendor in the optical industry. The lens, which has a base shape of a circle, is designed for use with a wavelength of 355 nm. It is made of UVFS Mal- 1965, a material specifically chosen for its optical properties.
The lens has a diameter of 12.7 mm and a thickness that varies from 3 mm at the edge to 2.3 mm at the center. This variation in thickness is due to the concave shape of the lens, which is designed to refract light in a specific way. The effective focal length (EFL) of this lens is -60 mm, which means that it will cause light to converge before or after the lens, depending on the position of the light source.
The lens is uncoated, meaning it does not have any additional layers to protect it or alter its optical properties. This can make it more susceptible to damage from environmental factors, but it also means that it does not introduce any additional distortions or reflections that a coating might cause.
For more information about this lens, including its specifications and where to purchase it, please refer to the vendor's website. The link provided is valid and indicates that the lens is in stock.